Romeo is an 11-year-old boy who lives humbly with his family in Sonogno, a small Swiss village near the border with Italy. The village is suffering a long drought, and Romeo's family has had the worst of it, as they are also under debt. Their last hope is the only corn field that has survived so many months without rain. Romeo wants to participate in the pole climbing competition, in which several boys compete to get a trophy placed on top of a pole. Meanwhile, Luini, a mysterious man known as the god of death, arrives in the village. He buys orphaned or poor children, which he later sells them as chimney sweeps in Milan, and now he has his eyes on Romeo.

Due to the injures suffered during the fire, Roberto's condition worsens to the point of going blind if he is not treated urgently. However, the family's financial situation prevents them from paying for the services of Baresi, the only doctor in the area. Romeo, aware of the situation, secretly signs a contract with Luini to go to work in Milan as a chimney sweep in exchange for the latter bringing the doctor to treat his father. The contract will be for six months, so Luini would be back to the village in spring. However, Anita hears that no children sold in Milan have returned.

After being treated by doctor Baresi, Roberto will recover and will not go blind. Romeo has sacrificed himself for the sake of his family and must now leave the village. On his way to Milan, Luini tells Romeo to go to the town of Locarno and wait for him there. Along the way, Romeo is mistaken for an apple thief, but is saved by Alfredo, a boy who is also heading to Milan to become a chimney sweep as Romeo. In Locarno, Alfredo's bag falls into a river after being stolen, so Romeo throws himself into the river to recover it.

The boat in which Romeo and the others are travelling to Milan is hit by a storm and sinks. Miraculously, Alfredo and Romeo manage to save themselves. Luini is also saved from drowning by Romeo. On the shore, Alfredo tells Romeo about his tragic past and how he was separated from his sister Bianca. The next morning, they leave for Milan.

Cleaning chimneys is harder than Romeo could imagine. And worst of all is that when he comes home tired from work he doesn't get a piece of bread. Rossi's family seems to hate him. However, an angel who lives in the house cares for him.

Spring has fallen and Romeo's contract with Maestro Rossi is over. It is time for Romeo to say goodbye to Milan and return home in Sonogno. Some of his friends have already left, while others still have to stay a while longer. Professor Casella offers to drive Romeo and the other boys halfway to their home towns along with Bianca. Before leaving, they visit Alfredo's grave one last time, where they meet the Wolf Pack.